1. Field of the Invention
The present invention generally relates to acceleration detection devices, methods of detecting acceleration, input devices, and recording media, and more particularly to an acceleration detection device which detects acceleration based on input signals from a sensor, a method of detecting acceleration which method employs such an acceleration detection device, an input device including such an acceleration detection device, and a recording medium storing a program for detecting acceleration.
Recently, a variety of ideas have been proposed in the field of game apparatuses, and a variety of input methods have been required, accordingly. Required as one of such input methods is an input device for detecting movements of arms and legs. Detection of acceleration may be employed as a method of detecting the movements of arms and legs. An acceleration detection sensor employing a spindle or weight and a spring generates vibrations due to the elasticity of the spring, and therefore, is prone to generate a signal having unnecessary components.
2. Description of the Related Art
FIG. 1 is a diagram for illustrating an input method for a game apparatus.
The game apparatus shown in FIG. 1 includes input devices 1, a game machine 2, and a display 3. The input devices 1 are attached to arms and legs 5 of a player 4 to detect accelerations. The accelerations detected by the input devices 1 are transmitted to the game machine 2 by means of infrared.
When the player 4 moves the arms and legs 5, accelerations are generated in accordance with the movements of the arms and legs 5. The input devices 1 detect these accelerations, and transmit the accelerations to the game machine 2. The game machine 2 detects forces exerted on the arms and legs 5 by the accelerations transmitted from the input devices 1, and causes a game character 6 shown in the display 3 to make actions.
FIG. 2 is an exploded perspective view of the conventional input device 1. The input device 1 includes a main body 11 and an attachment band 12.
The main body 11 is attached to one of the arms and legs 5 by means of the attachment band 12 so as to detect accelerations in accordance with the movements of the one of the arms and legs 5 and transmit the detected accelerations to the game machine 2. The main body 11 includes a case 21, a cover 22, a printed circuit board 23, and switch buttons 24.
The printed circuit board 23, on which an acceleration sensor 25, electronic components 26, and a cell 27 are mounted, is housed in a space formed by the case 21 and the cover 22.
FIG. 3 is an exploded perspective view of the conventional acceleration sensor 25.
The acceleration sensor 25 includes Hall elements 33 and an acceleration detection mechanism 32, which are arranged on the printed circuit board 23.
The acceleration mechanism 32 includes a base 41, a housing 42, a lever 43, a helical compression spring 44, a slider 45, and a cover 46. The lever 43 is supported by a support portion 47 of the base 41. The slider 45 is slidably held by the lever 43. The helical compression spring 44 is held in a compressed state between the slider 45 and the housing 42. The housing 42, through which the top end portion of the lever 43 penetrates in a direction indicated by arrow A in FIG. 3, is fixed to the base 41 so that the slider 45 and the helical compression spring 44 are housed between the base 41 and the housing 42.
The lever 43 includes a main body 51, a spindle or weight 52, a permanent magnet 53, and a cap 54. The spindle or weight 52 is fixed to the top end portion of the main body 51, which portion extends outward from the housing 42. The permanent magnet 53 is fixed to the bottom portion of the main body 51. The cap 54 is attached to the bottom portion of the main body 51 to cover the permanent magnet 53.
The cover 46 is fixed to the top end portion of the main body 51 to restrict movements of the main body 51. The acceleration detection mechanism 32 is fixed on the Hall elements 33 arranged on the printed circuit board 23.
FIGS. 4A and 4B are diagrams for illustrating an operation of the conventional acceleration sensor 25. FIG. 4A shows a state in which no acceleration is exerted, and FIG. 4B shows a state in which an acceleration is exerted.
In the state shown in FIG. 4A, the slider 45 is pressed toward the base 41 by the elasticity of the helical compression spring 44 so that the lever 43 is in an upright position.
On the other hand, when the acceleration is exerted on the spindle or weight 52, the lever 43 rotates on the support portion 47 of the base 41, while resisting the elasticity of the helical compression spring 43, as shown in FIG. 4B. As a result, the permanent magnet 53 shifts its position with respect to the Hall elements 33 to change the strength of a magnetic field applied to the Hall elements 33. Since the Hall elements 33 change their outputs depending on the strength of the magnetic field applied thereto, the tilt of the lever 43 is detectable based on the outputs of the Hall elements 33, thus allowing the detection of the acceleration exerted on the spindle or weight 52. Two pairs of the Hall elements 33 are arranged along an X-axis and a Y-axis as shown in FIG. 3 to detect the X-axis and Y-axis components of the acceleration, respectively.
Japanese Laid-Open Patent Application No. 11-353109 discloses the above-described mechanism in detail.
The input device 1 detects the magnitude and direction of the acceleration from the X-axis and Y-axis components detected in the above-described manner, and transmits the detected magnitude and direction of the acceleration to the game machine 2.
However, a conventional acceleration detection device simply detects a signal transmitted from an acceleration sensor as the acceleration, so that even unnecessary components of the signal are detected as noises.
It is a general object of the present invention to provide an acceleration detection device, a method of detecting acceleration, an input device, and a recording medium in which the above-described disadvantage is eliminated.
A more specific object of the present invention is to provide an acceleration detection device, a method of detecting acceleration, an input device, and a recording medium that allows necessary acceleration components to be extracted with accuracy.
The above objects of the present invention are achieved by an acceleration detection device for detecting an acceleration applied in a certain direction based on detection signals corresponding to the acceleration and including a waveform detection part detecting waveforms of the detection signals and an acceleration determination part determining whether to make valid or invalid the acceleration based on the waveforms detected in the waveform detection part.
The above objects of the present invention are also achieved by a method of detecting an acceleration applied in a certain direction based on detection signals corresponding to the acceleration, which method includes the steps of (a) detecting waveforms of the detection signals, and (b) determining whether to make valid or invalid the acceleration based on the detected waveforms.
The above objects of the present invention are also achieved by an input device including an acceleration detection mechanism outputting detection signals corresponding to an acceleration, a waveform detection part detecting waveforms of the detection signals output from the acceleration detection mechanism, and an acceleration determination part determining whether to make valid or invalid the acceleration based on the waveforms detected in the waveform detection part.
The above objects of the present invention are further achieved by a computer-readable recording medium recorded with a program which causes a computer to detect waveforms of detection signals corresponding to an acceleration and to determine whether to make valid or invalid the acceleration based on the detected waveforms.
According to the present invention, an acceleration is made valid by detecting only signals of waveforms matching the characteristic of a mechanism for detecting acceleration, thus preventing unnecessary acceleration components from being detected.